When concrete is being mixed in the concrete bowl of a truck, it is common that drying concrete residue becomes stuck on the interior walls of the bowl. It is desired to remove tacky concrete for a number of reasons including minimising exposure to rust, damage to the walls of the bowl and decreasing available volume within the bowl.
Due to the fact that concrete hardens rapidly, this cleaning process is required on a reasonably regular basis to stop excessive build up of concrete residue.
Therefore a system to clean the concrete bowl in an efficient, effective, safe, and environmentally friendly way is desired.
Utilising water from a recycled supply for the removal of residual tacky concrete from bowls is common practice. However, these systems generally involve a water pipe dropping water into the back of the bowl with the bowl rotating to rinse the water throughout the bowl. No pressurized water is used
Occasionally, a worker may also hold a water nozzle which distributes fresh water at mains supply pressure to remove this hardened concrete.
There are a number of disadvantages to these methods.
Firstly, these are slow and inefficient processes. Concrete bowls are generally reasonably large in size. The time required to discharge an effective amount of rinsing water and to rotate the bowl is lengthy. Also, the time it takes for the worker to apply the water nozzle to the interior surface area of a concrete bowl is lengthy.
Also due to the size of the concrete bowl, a large volume of water is required. Therefore this may not be the most efficient process in terms of time and water usage. The conventional method of dropping water into the truck bowl does not prevent significant accumulation of hardened concrete over time. Alternatively, the method of a worker holding a water nozzle which distributes fresh water at mains supply pressure uses a large volume of water, which is not very environmentally friendly.
A problem with a worker spraying water into the bowl is that there are certain ‘blind spots’ that cannot be cleaned due to the limited reach of the worker with his/her water nozzle. Most of the concrete bowls used in the industry today includes fins that protrude from the interior walls. It is difficult for the worker to apply the pressured water using these water nozzles to remove drying concrete behind these fins due to the reach or positioning of the worker. Also, because the method of cleaning is user operated, the chances of missing spots are high.
To remove hardened, cured concrete that may accumulate in the truck bowl over time, a worker is required to enter the truck bowl and use a pneumatic or electric jackhammer. There are obvious health and safety factors which may exist with this method with higher chances for injuries to workers as the equipment can be heavy, and fractured concrete may fall on the worker. This method may require the worker to undergo specialised training. Special rules will also apply to worker entering a confined space to meet Occupational Safety and Health (OSH) standards.
The invention described in New Zealand Application No. 583104 aims to overcome the above problems by introducing an automated system which means the user no longer has to enter the truck bowl and jackhammer concrete from the walls and fins. However, some major problems still subsists with the system disclosed in this patent document.
First, this system in practice is only used sporadically—not as an ongoing preventative program. This leads to concrete in the bowl accumulating and hardening between uses of the equipment.
Further, it still uses a large volume of water. Due to the large size of the concrete bowls, the amount of water required to clean the bowl is substantive.
The system operates at very high pressure, and any worn surfaces within the bowl may be damaged by the high pressure water spray.
Because this system utilises the mains water supply source it is still not environmentally friendly given the size of the concrete bowls.
Finally, this system still requires the worker to enter the concrete bowl after the cleaning process to check whether if cleaning was sufficient. Therefore the same confined space training and requirements still apply for OSH standards. It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
Throughout this specification, the word “comprise”, or variations thereof such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.